Presentation Title

Nearshore and offshore feeding of juvenile salmon and forage fish in the Salish Sea

Session Title

Session S-02D: Pelagic Ecology in the Salish Sea II

Conference Track

Species and Food Webs

Conference Name

Salish Sea Ecosystem Conference (2014 : Seattle, Wash.)

Contributing Repository

Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.

Start Date

30-4-2014 1:30 PM

End Date

30-4-2014 3:00 PM

Abstract

The Salish Sea provides essential early marine growth environment for several pelagic fish species, including Pacific salmon (Oncorhynchus spp), Pacific herring (Clupea pallasi), and other forage fish (e.g., surf smelt, Hypomesus pretiosus; sand lance, Ammodytes hexapterus). Early marine feeding and growth can be important to survival to adulthood for these species. Early marine growth of Endangered Species Act-listed Puget Sound Chinook salmon (O. tshawytscha) is tightly correlated with smolt to adult returns. Variability in early growth is linked to variation in feeding rate. Therefore, factors which affect feeding success, such as competition, during this life stage could have important influences on marine survival. Recent work has shown spatial-temporal and dietary overlap among juvenile salmon and herring and suggested that potential for competitive interactions exists. However, the extent and strength of potential interactions remain poorly understood and little is known about the feeding of other pelagic planktivores. We describe feeding habits of juvenile salmon, herring, and surf smelt in the Salish Sea to quantify variation in diet composition and characterize dietary overlap. Monthly, yearly, and regional variation was evident, but consistent patterns were distinguishable. During the critical summer growing season, Pacific herring dominated the biomass of the shallow pelagic planktivorous fish community and exhibited extensive diet and spatial overlap with juvenile Chinook salmon and coho salmon (O. kisutch). Crab larvae and amphipods were important prey items. Diet compositions of chum salmon (O. keta) and surf smelt differed from those of the other species, including greater amounts of gelatinous organisms (ctenophores, larvaceans). Our results suggest that assessments of basin carrying capacity and potential species interactions need to account for the population and feeding dynamics of all major daylight planktivores, especially herring.

Rights

This resource is displayed for educational purposes only and may be subject to U.S. and international copyright laws. For more information about rights or obtaining copies of this resource, please contact University Archives, Heritage Resources, Western Libraries, Western Washington University, Bellingham, WA 98225-9103, USA (360-650-7534; heritage.resources@wwu.edu) and refer to the collection name and identifier. Any materials cited must be attributed to the Salish Sea Ecosystem Conference Records, University Archives, Heritage Resources, Western Libraries, Western Washington University.

Language

English

Format

application/pdf

Type

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Apr 30th, 1:30 PM Apr 30th, 3:00 PM

Nearshore and offshore feeding of juvenile salmon and forage fish in the Salish Sea

Room 611-612

The Salish Sea provides essential early marine growth environment for several pelagic fish species, including Pacific salmon (Oncorhynchus spp), Pacific herring (Clupea pallasi), and other forage fish (e.g., surf smelt, Hypomesus pretiosus; sand lance, Ammodytes hexapterus). Early marine feeding and growth can be important to survival to adulthood for these species. Early marine growth of Endangered Species Act-listed Puget Sound Chinook salmon (O. tshawytscha) is tightly correlated with smolt to adult returns. Variability in early growth is linked to variation in feeding rate. Therefore, factors which affect feeding success, such as competition, during this life stage could have important influences on marine survival. Recent work has shown spatial-temporal and dietary overlap among juvenile salmon and herring and suggested that potential for competitive interactions exists. However, the extent and strength of potential interactions remain poorly understood and little is known about the feeding of other pelagic planktivores. We describe feeding habits of juvenile salmon, herring, and surf smelt in the Salish Sea to quantify variation in diet composition and characterize dietary overlap. Monthly, yearly, and regional variation was evident, but consistent patterns were distinguishable. During the critical summer growing season, Pacific herring dominated the biomass of the shallow pelagic planktivorous fish community and exhibited extensive diet and spatial overlap with juvenile Chinook salmon and coho salmon (O. kisutch). Crab larvae and amphipods were important prey items. Diet compositions of chum salmon (O. keta) and surf smelt differed from those of the other species, including greater amounts of gelatinous organisms (ctenophores, larvaceans). Our results suggest that assessments of basin carrying capacity and potential species interactions need to account for the population and feeding dynamics of all major daylight planktivores, especially herring.